Table 4.
Methodological differences between the present study and Kanai et al. (2012).
| Difference | Here | Kanai et al. (2012) | Reason |
|---|---|---|---|
| Sample size and design | n = 26, within-subject design | n = 32, between-subject design | More observations per cell, less influence of between-subject variability |
| FEF localization | MRI-guided per individual | Group MRI coordinate | More power (Sack et al., 2009) |
| tDCS: duration | 15 min | 10 min | More trials during stimulation; possibly increase tDCS effect |
| tDCS: location | Right FEF | Right or left FEF | Right FEF is dominant (Duecker and Sack, 2015) |
| tDCS: montage | FEF, contralateral forehead | FEF, ipsilateral shoulder | Decreased interelectrode distance increases effect (Moliadze et al., 2010; Opitz et al., 2015). Resembles canonical motor cortex montage |
| tDCS: conductive medium | Ten20 conductive paste | Saline soaked sponges | Uniform electrode-skin contact, no risk of excess/leaking saline |
| Number of saccades per condition | 180 (per 15 min) | 40 (per 10 min) | More robust estimates within each participant |
| Task: stimulus overlap | No overlap of fixation and target | Fixation point always on | Possibility to analyze saccades back to fixation (center) |
| Task: placeholders | None | Target location marked with placeholders | Spatial uncertainty might create more room for improvements in accuracy with tDCS |
| Task: ISI | Exponential distribution: mean 500 ms, bounds 300–3,000 ms | Normal distribution, bounds: 300–700 ms | Temporally more unpredictable target onsets |
| Eye tracker: sampling rate | 1,000 Hz | 250 Hz | More adequate resolution for small effects |
| Eye tracker: saccade threshold | >30°/s velocity and >8000°/s2 acceleration | >26.8°/s velocity | Eyelink standards |